Drilling fixture for a diminutive elongated drill

ABSTRACT

Drilling fixture for a diminutive, elongated drill, including a rotary driven drill holder for rotating said drill relative to a work-piece and reciprocable means for providing a relative reciprocal movement in an axial drilling direction between said drill and said work-piece. Stabilizing means is provided to stabilize the elongated drill against a whipping motion and comprises at least first and second drill support means mounted in axial alignment with respect to each other between said drill holder and said work piece for radially supporting said elongated drill along its axis. At least one of said drill support means is movable along the axis of the drill to vary the axial spacing between said drill support means.

United States Patent Wolf [ 1 Dec. 26, 1972 [54] DRILLING FIXTURE FOR ADIMINUTIVE ELONGATED DRILL [72] Inventor: Fred K. Wolf, 3562 W. 147thStreet, Cleveland, Ohio 44111 [22] Filed: May 18,1970

211 App]. No.: 38,404

[52] U.S. Cl ..408/l43, 408/705 [51] Int. Cl. ..B23b 49/00 [58] Field ofSearch ..408/705, 143, 199, 97, 51; 90/14 [5 6] References Cited UNITEDSTATES PATENTS 2,507,503 5/1950 Cudini... 408/705 X 3,555,964 1/1971Fleming ..90/14 2,536,333 l/l95l Waxelbaum "408/705 X 2,795,977 6/1957Carlstedt ..408/705 X 2,251,701 8/1941 Dixon ..408/705 X PrimaryExaminerAndrew R. Juhasz Assistant Examiner-Z. R. BilinskyAttorney-Woodling, Krost, Granger and Rust [5 7 ABSTRACT Drillingfixture for a diminutive, elongated drill, including a rotary drivendrill holder for rotating said drill relative to a work-piece andreciprocable' means .for providing a relative reciprocal movement in anaxial drilling direction between said drill and said work-piece.Stabilizing means is provided to stabilize the elongated drill against awhipping motion and comprises at least first and second drill supportmeans mounted in axial alignment with respect to each other between saiddrillholder and said work piece for radially supporting said elongateddrill along its axis. At

least one of said drill support means is movable along the axis of thedrill to vary the axial spacing between said drill support means.

20 Claims, 1 Drawing Figure SUPPLY SOURCE PATENTEDumzs I972 INVENTORFRED K wo DRILLING FIXTURE FOR A DIIVIINUTIVE ELONGATED DRILL BACKGROUNDOF THE INVENTION A diminutive, elongated drill is prone to develop awhipping'motion when driven at an effective cutting speed relative to awork piece. One particular application for these small drills is that ofdrilling small diameter, deep flush holes in graphite electrodes used inelectrical discharge machines through which fluid is pumped for flushingout the formation of sludge. The drills are available in severaldiameters, ranging from approximately 0.0135 to 0.052 inch. Their lengthmay vary from 4 to 6 inches.

High speed and jerky feeds are two conditions that may cause a whippingmotion. Of course, high speed is very desirable in order to minimize thedrilling cost. Jerky feedstend to bow the drill due to sudden endthrusts. v

The prevailing practice has been to ignore drilling cost and resort to aprocedure of operating the drill at a speed which is just below thepoint at which the drill wound normally begin to whip. With respect to ajerky feed, this is something that the trade has attempted to overcomeby steady hands.

Accordingly, it is an object of my invention to operate the drill athigh speed, here a whipping action would normally occur, and thenprevent the shipping action, whereby rapid drilling is achieved forreducing the drilling cost.

Another object is to stabilize the elongated drill along its axis toprevent whipping.

Another object is the provision of at least two drill supports forstabilizing the drill along its axis between the rotary drill holder andthe work piece, wherein at least one of the drill supports is axiallymovable along the axis of the drill to vary the axial spacing betweenthe drill supports.

Another object is to vary the axial spacing automatically.

Another object is to space at least two drill supports axially apartalong the axis of the drill to provide an interval therebetween and toreduce the extent of the interval as the drilling progresses.

Another object is the provision of reciprocable means for providing arelative reciprocal movement in an axial drilling direction between thedrill and the work piece and of stabilizing the drill along its axis inresponse to the reciprocal movement.

Another object is the provision of supporting the drill along its axisat the beginning of the drilling operation by at least two axiallyspaced apart drill supports and of reducing the extent that the drillsupports are axially spaced apart as the drilling progresses.

Another object is to adjustably feed the drill into the work piece byturning a micrometer and thereby avoid jerky feeding.

SUMMARY OF THE INVENTION The invention constitutes a drilling fixturefor a diminutive, elongated drill, including a rotary driven drillholder for rotating said drill relative to a work piece andrecipr'ocable means for providing a relative reciprocal movement in anaxial drilling direction between said drill and said work piece, saidelongated drill possessing in proneness to develop a whipping motionwhen driven at an efi'ective cutting speed relative to said work piece,and stabilizing means to stabilize said elongated drill againstsaidwhipping motion, said stabilizing means comprising at least first andsecond drill support means mounted in axial alignment with respect toeach other between said drill holder and said work piece for radiallysupporting said elongated drill, at least one of said drill supportmeans being movable along the axis of said drill to vary the axialspacing between said drill support means.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a view illustrating thestructural and operative features of my invention, the diminutive drillbeing diagrammatically illustrated by a single line, which, of course,is still larger than the actual size of the drill; the line shading ofthe drawing has been applied only to the round parts, whereby they maybe readily distinguishable from the flat surfaces.

DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated, my drillingfixture is adapted to operate a diminutive, elongated drill 10 relativeto a work piece 11. In the illustration, the work piece may comprise agraphite electrode used 'in electrical discharge machines. The drill 10may have a diameter residing in a range of approximately 0.0135 to 0.052inch. lts length may vary from 4 to 6 inches. Of course, larger drillsmay be used in my fixture, but the real problem arises when drillingsmall diameter, deep holes through which fluid may be pumped forflushing out the formation of sludge. Being diminutive in diameter, theelongated drill 10 is longitudinally flexible and thus tends to developa whipping action when driven at an effective cuttingspeed.

My drilling fixture, in general, may comprise, a base Y 14, front andback upright members 15 and 16, a main carrier 17, and a system ofstabilizing drill support members, indicated generally by the referencecharacter 18. The upright members 15 and 16 may be suitably fastened tothe base 14 and are arranged to support two main guide rods 19 and 20above the level of the base 14 and upon which the main carrier 17 may beslidably and reciprocably mounted, as indicated by the reversing arrows,for providing a relatively reciprocal movement in an axial drillingdirection between the drill l0 and the work piece 11. The main carrier17 is preferably arranged to reciprocate freely on the two main guiderods 19 and 20. Mounted in the main carrier 17 is a rotary drill holder22 driven by an electric motor 23 connected to a supply source 24 andcontrolled by a speed device 25. the reciprocal movements of the maincarrier 17 may be limited in its forward direction (to the left) by anadjustable forward stop 27 carried upon a rod 28 and in its rearwarddirection (to the right) by an adjustable rear stop 29 carried on therod 28. The rod 28 extends freely through the main carrier l7 and hasits front end fixedly connected to the front upright member 15. Asillustrated, the work piece 11 may be mounted in any suitable workholder 30 connected to the base 14, as illustrated by the dash-dot line49.

The system of stabilizing drill support members 18 comprise at leastfirst and second drill support bushings 32 and 33 carried respectivelybycross-members 35 and 36. The ends of the cross-member 35 are fixedlyconnected to a first pair of guide rods 37 and 38 which slidably extendthrough .the main carrier 17, as well'as through the rear upright member16. Accordingly, the drill support bushing 32 carried by thecross-member 35 may be reciprocably actuated relative to the maincarrier 17 and also relative to the drill 10. The ends of thecross-member 36 are fixedly connected to a second pair of guide rods 39and 40 which slidably extend through the main carrier 17, as well asthrough the rear upright member 16. The drill support bushings 33carried by the cross-member 36 may thus be reciprocably actuatedrelative .to the main carrier 1'7 and also relative to the drill 10. Thereciprocal movements of the pair of guide rods 37 and 38 may be-limitedin their rearward direction (to the right) by adjustable stops 43 and44. Similarly, the reciprocal movements of the pair of guide rods 39 and40 may be limited in their rearward direction by adjustable stops 45 and46. The

ments of the cross-member 35, which carries the drill support bushing32, is limited in its forward direction when it engages the back side ofthe cross-member 36. The front upright member 15 is provided with adrill support bushing 34 which is in axial alignment with the two drillsupport bushings 33 and 32, respectively carried by the cross-members 36and 35.

The feed advancement of the drill 10 into the work piece 11 may begoverned by a micrometer 47 suitably mounted on the side of the maincarrier 17. The end of the micrometer 47 is adapted to engage the rearend of a micrometer stop rod 48 having its forward end adjustablyconnected to a side of the front upright member 15.

In setting up the operation for drilling a deep hole into the workpiece, the drill 10 is first mounted in the drill holder 22. The drillis mounted from the front side of the front upright member 15, throughthe stationary drill support bushing 34 and then through the tworeciprocal drill support bushings 33 and 32. The adjustable stop 29,which limits the rearward movement of the main carrier 17, is thenadjusted so that the drill l0 protrudes from the front side of thestationary drill support bushing 34 for a distance of approximately oneor two diameters of the drill. Next, the adjustable stop 27, whichlimits the forward movement of the main carrier 17, is set to obtain thedesired hole depth. The micrometer is set at zero depth and themicrometer stop rod 48 is set to contact the micrometer. The work piece11 may now be clamped in the work holder and adjusted to a gappreferably of not more than four diameters from the front of the drill10. The stops 43 and 44 on the bushing guide rods 37 and 38 and thestops 45 and 46 on the bushing guide rods 39 and are set, .whereby thespacing (interval) between the drill bushings 34 and 33 is about thesame as the spacing between the drill bushings 33 and 32, as well as thespacing between the bushing 32 and the drill holder 22.- The elongateddrill 10 is thus supported substantially at even intervals along theaxis thereof when the main carrier 17 is moved against the rear stop 29.The main carrier 17 is provided with wiper rings 53, 54, 55 and 56 whichrespectively surround the bushing guide rods 37, 38, 39 and 40 toprovide a friction therebetween, whereby reciprocal movements of themain carrier 17 are frictionally transmitted to the bushing guide rods 7for varying the spacing along the axis of the drill 10.

In operation, the drill motor 23 is started and the speed may be set bythe speed control device 25. With start on center. After the drill hasbeen advanced for. a drilling distance of approximately four to eightdiameters, it is retracted out of the work piece to clear the chips. Themicrometer 47 remains unchanged during retraction and the main carrier17 is moved backwards until it engages the. rear stop 29. The -reentryof the drill in the hole may be advanced rapidly until the micrometer 47again engages the micrometer stop rod 48. The drill is now in the samedrilling position as it was before retraction. For further drilling, themicrometer is revolved until the drill is advanced for another distanceof approximately four to eight diameters, after which it is againretracted to remove the chips. These drilling and retracting operationsare repeated until the main carrier 17 engages the front stop 27, whichis the setting for the depth of the hole. In the drilling operation,when the micrometer 47 reaches the end of its travel (l-inch) themicrometer rod48 is reset to a new position to permit the micrometer-tooperate again within the range of its travel for feeding the drill 10into the work piece.

In my invention, the drill 10 may be repeatedly retracted from the workpiece to clean out the chips. It is to be observed that upon eachretraction of the main carrier 17 in a rearward direction against therear stop 29, the drill support bushings 32 and 33 are restored to theiroriginal positions. It is during the time when the main carrier 17 isbeing returned to its drilling position that the relative positions ofthe bushings may'become axially varied. Thus, the spacing (interval)between the bushings 33 and 34 becomes less and less, by incrementssubstantially equal to the previous drilling depth, upon each returnadvancement of the drill 10 into the work piece after cleaning. Theinterval continues to decrease until the bushing 33 engages the backside of the front upright member 15. As the drilling advances stilldeeper, the interval between the bushing 33 and 32 starts to decrease,increment by increment, upon each return advancement of the drill 10into the work piece after cleaning. The decrease continues until thebushing 32 engages the backside of the cross-member 36. Now, theinterval between the bushing 32 and the drill holder 22 starts todecrease upon each return advancement of the drill 10 into the workpiece after cleaning. It continues to decrease until the main carrier 17engages the front stop 27, which is the stop that determines the holedepth. It is to be noted that upon each return advancement of the drillintothe work piece after cleaning,.the spacing of the drill supportbushings along the axis of the drill become less and less until the holedepth is obtained and that upon each retraction of the main carrier 17against the rear stop 29, the drill support bushings 32 and 33 arerestored to their original positions. Accordingly, it is observed thatwhen the drill is retracted from the work piece during cleaning, thedrill support bushings are substantially evenly spaced along the axis ofthe drill to prevent whipping of the drill, as would otherwise tend tooccur since the drill is fully extended from the work piece. When thedrill 10 is fully within the work piece, there is little, if any,tendency for the drill to whip, since it is supported by the hole. Myinvention accommodates for this situation, because when the drill isreturned into the work piece after each retraction, the spacing betweenthe drill support bushings become axially compressed, being a positionof the bushings which may be characterized as a collapsed condition.When in the collapsed condition, the drill support bushings make roomfor the drill holder 22 to advance without interference from the drillsupport bushings. In my invention, the axial spacing of the drillsup'port bushings is preferably achieved automatically in response tothe reciprocal movements of the main carrier 17, but'this achievementmay be produced otherwise. The present disclosure includes thatcontained in the appended claims, as well as that of the foregoingdescription. Although this invention has been described in its preferredform with a certain degree of particularlity, it is understood that thepresent disclosure of the preferred form has been made only by way ofexample and that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

1. A drilling fixture for a diminutive, elongated drill, including arotary driven drill holder for rotating said drill relative to a workpiece and reciprocable means including carrier means for providing arelative reciprocal movement in an axial drilling direction between saiddrill and said work piece, said elongated drill possessing a pronenessto develop a whipping motion when driven at an effective cutting speedrelative to said work piece, and stabilizing means to stabilize saidelongated drill against said whipping motion, said stabilizing meanscomprising at least first and second drill support means mounted inaxial alignment with respect to each other between said drill holder andsaid work piece for radially supporting said elongated drill,

rod means slidably supported on said carrier means for carrying said atleast one of said drill support means, and friction means between saidrod means and said carrier means to reciprocably move said at least oneof said drill support means in response to said reciprocal movement ofsaid carrier means.

2. The structure of claim 1, including stop means on said rod means tolimit the travel thereof.

3. The structure of claim 1, having micrometer means to adjustably feedsaid drill into said work piece.

4. The structure of claim 1, having stop means to limit the extent ofthe total depth of said drill, in said work piece.

5. The structure of claim 1, having means for axially spacing at leastone of said drill support means from the other to provide an intervaltherebetween, and means responsive to saidreciprocalmovement to reducethe axial extent of said interval.

6. The structure of claim 1, wherein the other of said drill supportmeans is stationarily mounted between said drill holder and said workpiece.

7. A drilling fixture for a diminutive, elongated drill, including arotary driven drill holder for rotating said drill relative to a workpiece and reciprocable means including carrier means for providing arelative reciprocal movement in an axial drilling direction between saiddrill and said work piece, said'e'longated drill possessing a pronenessto develop a whipping motion when driven at an effective cutting speedrelative to said work piece, and stabilizing means to stabilize saidelongateddrill against said whipping motion, said stabilizing meanscomprising at least first and second drill support means mounted inaxial alignment with respect to each other between said drill holder andsaid work piece for radially supporting said elongated drill, first andsecond rod means slidably supported on said carrier means forrespectively carrying said first and second drill support means, andfriction means between said first and second rod means and said carriermeans to reciprocably move said first and second drill support means inresponse to said reciprocal movement of said carrier means.

8. The structure of claim 7 including stop means respectively on saidfirst and second rod means to limit the travel thereof.

9. The structure of claim 7, wherein said stabilizing means includes athird drill support means mounted in axial alignment with said first andsecond drill support therebetween and for axially spacing said seconddrill support means from said third drill support means to provide asecond interval therebetween, and means responsive to said reciprocalmovement to reduce the axial extent of said intervals.

12. Drilling means for a diminutive, elongated drill, including a rotarydriven drill holder for rotating said drill relative to a work piece,drill holder carrier means for carrying said drill holder, mountingmeans upon which said drill holder carrier means may be reciprocablymounted to provide a reciprocal movement for reciprocably actuating saiddrill in an axial direction toward and away from said work piece, saidelongated drill possessing a proneness to develop a whipping motion whendriven at an effective cutting speed relative to said work piece,stabilizing means to stabilize said elongated drill against saidwhipping motion, said stabilizing means including at least first andsecond drill support means disposed between said drill holder and saidwork piece for radially supporting said elongated drill, said first andsecond drill support means being mounted in axial alignment with respectto each other for radially supporting said elongated drill meansrelative to the other to vary the width of said interval. v

13. The' structure of claim, 12, wherein said other of said drillsupport means is stationarily mounted between said drill holder and saidwork piece.

1 14. The structure of claim 12, including stop means to adjustably varythe extent that said drill holder carrier means may be reciprocablyactuated on said mount-,

ing means. g

15. The structure of claim 12, including adjustable stop means to varythe limits of the travel of said at least one of said drill supportmeans.

16. The structure of claim 12, including third drill support meansdisposed between said drill holder and said work piece for radiallysupporting said elongated drill, said third drill support means beingmounted in support means includes rod support means slidably' axialalignment with said at least one of said-drill supbeing disposed forreciprocal movement relative to said at least one of said drill supportmeans, and second yieldable means to reciprocably move said third drillsupport means relative to said at least one of said drill support meansto vary thewidth of said axial space.

17. The structure of claim 16, wherein said second yieldable means ismovable with said drill holder carrier means for actuating said thirddrill support means in response to said reciprocal movement of saiddrill holder carrier means.

18. The structure of claim 16, wherein said third drill mounted on saiddrill holder carrier means.

19. The structure of claim 12, wherein said yieldable means'is movablewith said drill holder carrier means for actuating said at least one ofsaid drill support means in response to said reciprocal movement of saiddrill holder carrier means. a

' 20. The structure of claim 12, including stop means comprising firstand second contact means, said first contact means being disposed toengage said'second contact means, said first contact means being movablewith said at least one of said drill support means and being disposed tolimit the travel thereof upon engagement with said second contact means,said yieldable means being inoperativeto move said at least one of saiddrill support means upon said engagement of said first contact meanswith said second contact means.

1. A drilling fixture for a diminutive, elongated drill, including arotary driven drill holder for rotating said drill relative to a workpiece and reciprocable means including carrier means for providing arelative reciprocal movement in an axial drilling direction between saiddrill and said work piece, said elongated drill possessing a pronenessto develop a whipping motion when driven at an effective cutting speedrelative to said work piece, and stabilizing means to stabilize saidelongated drill against said whipping motion, said stabilizing meanscomprising at least first and second drill support means mounted inaxial alignment with respect to each other between said drill holder andsaid work piece for radially supporting said elongated drill, rod meansslidably supported on said carrier means for carrying said at least oneof said drill support means, and friction means between said rod meansand said carrier means to reciprocably move said at least one of saiddrill support means in response to said reciprocal movement of saidcarrier means.
 2. The structure of claim 1, including stop means on saidrod means to limit the travel thereof.
 3. The structure of claim 1,having micrometer means to adjustably feed said drill into said workpiece.
 4. The structure of claim 1, having stop means to limit theextent of the total depth of said drill in said work piece.
 5. Thestructure of claim 1, having means for axially spacing at least one ofsaid drill support means from the other to provide an intervaltherebetween, and means responsive to said reciprocal movement to reducethe axial extent of said interval.
 6. The structure of claim 1, whereinthe other of said drill support means is stationarily mounted betweensaid drill holder and said work piece.
 7. A drilling fixture for adiminutive, elongated drill, including a rotary driven drill holder forrotating said drill relative to a work piece and reciprocable meansincluding carrier means for providing a relative reciprocal movement inan axial drilling direction between said drill and said work piece, saidelongated drill possessing a proneness to develop a whipping motion whendriven at an effective cutting speed relative to said work piece, andstabilizing means to stabilize said elongated drill against saidwhipping motion, said stabilizing means comprising at least first andsecond drill support means mounted in axial alignment with respect toeach other between said drill holder and said work piece for radiallysupporting said elongated drill, first and second rod means slidablysupported on said carrier means for respectively carrying said first andsecond drill support means, and friction means between said first andsecond rod means and said carrier means to reciprocably move said firstand second drill support means in response to said reciprocal movementof said carrier means.
 8. The structure of claim 7 including stop meansrespectively on said first and second rod means to limit the travelthereof.
 9. The structure of claim 7, wherein said stabilizing meansincludes a third drill support means mounted in axial alignment withsaid first and second drill support means between said drill holder andsaid work piece.
 10. The structure of claim 9, wherein said first andsecond drill support means are reciprocably movable along the axis ofsaid drill in response to said reciprocal movement of said reciprocablemeans, and wherein said third drill support means is stationarilymounted.
 11. The structurE of claim 9, including means for axiallyspacing said first drill support means from said second drill supportmeans to provide a first interval therebetween and for axially spacingsaid second drill support means from said third drill support means toprovide a second interval therebetween, and means responsive to saidreciprocal movement to reduce the axial extent of said intervals. 12.Drilling means for a diminutive, elongated drill, including a rotarydriven drill holder for rotating said drill relative to a work piece,drill holder carrier means for carrying said drill holder, mountingmeans upon which said drill holder carrier means may be reciprocablymounted to provide a reciprocal movement for reciprocably actuating saiddrill in an axial direction toward and away from said work piece, saidelongated drill possessing a proneness to develop a whipping motion whendriven at an effective cutting speed relative to said work piece,stabilizing means to stabilize said elongated drill against saidwhipping motion, said stabilizing means including at least first andsecond drill support means disposed between said drill holder and saidwork piece for radially supporting said elongated drill, said first andsecond drill support means being mounted in axial alignment with respectto each other for radially supporting said elongated drill along theaxis thereof with an interval therebetween, at least one of said drillsupport means including rod means slidably mounted on said drill holdercarrier means and being disposed for reciprocal movement relative to theother, and yieldable means to reciprocably move said at least one ofsaid drill support means relative to the other to vary the width of saidinterval.
 13. The structure of claim 12, wherein said other of saiddrill support means is stationarily mounted between said drill holderand said work piece.
 14. The structure of claim 12, including stop meansto adjustably vary the extent that said drill holder carrier means maybe reciprocably actuated on said mounting means.
 15. The structure ofclaim 12, including adjustable stop means to vary the limits of thetravel of said at least one of said drill support means.
 16. Thestructure of claim 12, including third drill support means disposedbetween said drill holder and said work piece for radially supportingsaid elongated drill, said third drill support means being mounted inaxial alignment with said at least one of said drill support means forradially supporting said elongated drill along the axis thereof with anaxial space between said at least one of said drill support means andsaid third drill support means, said third drill support means beingdisposed for reciprocal movement relative to said at least one of saiddrill support means, and second yieldable means to reciprocably movesaid third drill support means relative to said at least one of saiddrill support means to vary the width of said axial space.
 17. Thestructure of claim 16, wherein said second yieldable means is movablewith said drill holder carrier means for actuating said third drillsupport means in response to said reciprocal movement of said drillholder carrier means.
 18. The structure of claim 16, wherein said thirddrill support means includes rod support means slidably mounted on saiddrill holder carrier means.
 19. The structure of claim 12, wherein saidyieldable means is movable with said drill holder carrier means foractuating said at least one of said drill support means in response tosaid reciprocal movement of said drill holder carrier means.
 20. Thestructure of claim 12, including stop means comprising first and secondcontact means, said first contact means being disposed to engage saidsecond contact means, said first contact means being movable with saidat least one of said drill support means and being disposed to limit thetravel thereof upon engagement with said second contact means, saidyieldable means being inoperative to move said at lEast one of saiddrill support means upon said engagement of said first contact meanswith said second contact means.